Most people will ignore what other people say because they haven't had a bad experience with it, but if they have experienced repeated failures even though they have tried many times, that's where they will be based on the fact that the advice given by other people is the right one. For now, just let your friend continue gambling, all you can do is give him endless advice and direction, after all he is your friend.
I don't do blame games with some newbies, they have this mentality of first game isn't enough to verify if their losses is enough, they will try again but the wise one will quit immediately if they have a consecutive loss back to back and quit or try another day but the daft ones will keep playing until nothing comes from and lose all the games and the money and that time, it will be too late to make corrections, this is when guilt and self discipline start to work.
If you want to see the crazy part, the addicted ones will come back in with big pockets and then try again until everything is loss. If you have experience where a celebrity gamble right in front of you in a casino house, they display this behavior often, spend some money in casino and loss, bring another money to the table and loss everything and then walk home with the remaining money with the homies for weed and food chuncks.